This invention relates in general to lighting systems employing fiber optics and in particular to a fiber optic illuminating apparatus configured for coupling light emitted from a high-energy light source to the input end of a fiber optic cable for transmission to light emitting fixtures.
Illuminating apparatuses such as fiber optic lighting systems, for example, are used in a variety of applications to provide a cool, flexible, safe source of light. The assignee of the present invention provides fiber optic light systems for use in signs, displays, swimming pools, landscapes and general area lighting. One such fiber optic light system for providing multi-color light effects is described in U.S. Pat. No. 5,528,714 issued Jun. 18, 1996, to Kingstone et al., assigned to the assignee of the present invention and incorporated by reference herein. A fiber optic lighting system may typically include a light source having a fiber optic cable bundle for transmitting light from the light source to a location remote from the light source. The light source may include an enclosure containing a light bulb, a means for securing the end of a fiber optic cable bundle near the light bulb, a power supply or other electronic equipment, and a fan for providing cooling air to the enclosure.
One of the limiting characteristics of a fiber optic light system is the amount of light that can be delivered from the fiber optic cable. The output of the system depends upon numerous variables, such as the intensity of the light produced by the bulb, the effectiveness of the delivery of the light into the fiber end, and the efficiency of the transmission of the light by the fiber optic cable. A fiber optic light system is disclosed in U.S. Pat. No. 6,422,730 issued Jul. 23, 2002, to Koren et al., which is incorporated herein by reference, which provides multiple cooling devices to cool the ambient temperature of the system and the input end of a fiber optic cable.
It is known to increase the amount of light introduced at the inlet end of the fiber optic cable bundle in order to increase the amount of light produced by the system. However, light bulbs used to produce such light, for example incandescent and halogen lamps, produce a significant amount of heat energy along with the visible light energy. As the power of the light bulb is increased and the bulb is placed closer to the ends of the fiber optic cables it becomes increasingly difficult to provide cooling for the cable ends. It is known that plastic cable fibers will melt at approximately 175 degrees Fahrenheit. Even local melting of the cable may cause a depression in the cable end, thus causing the cooling air to become stagnant and intensifying the local heating effect. In this manner, even a small local hot spot will quickly destroy the functionality of a cable fiber. Therefore, in order to improve the performance of a fiber optic light source, it may be beneficial to provide additional means to protect the cable ends against melting. U.S. Pat. No. 5,838,860 issued Nov. 17, 1998, to Kingstone et al., assigned to the assignee of the present invention and incorporated herein by reference, describes the use of a plate of heat absorbing material as part of a temperature control scheme within the enclosure of a fiber optic illumination system. In many designs of fiber optic lighting systems the factor limiting the brightness that can be achieved in the fiber optic cable is the cooling of the cable ends.
Fiber optic light sources generally include an apparatus for positioning a bulb and an associated reflector along an optical axis to direct a beam of light through a lens to the fiber ends. Such an apparatus can be seen in FIG. 2 of the aforementioned U.S. Pat. No. 5,838,860. The reflector design described in that patent is a one piece glass reflector having a generally truncated ellipsoid reflecting portion formed to be integral with a rearward rectangular or rounded base portion. The bulb is typically affixed within the base portion of the reflector with a high temperature adhesive. The fiber optic cable ends are held in position by a ferrule assembly that is attached to the light source housing. The ferrule and reflector are positioned relative to each other by an optical bench.
In a light source for a fiber optic system it is beneficial to provide local cooling to the ends of the cable bundle fibers and general cooling for the bulb and other components included in the light source enclosure. The large amount of heat generated by the bulb and other electronics within the enclosure often requires a supply of a high volume of cooling air. However, for cooling the cable end, the volume of air is not as beneficial as is the velocity of the air, due to the geometry of the cable end and the relatively poor thermal conductivity of the air. In order to provide the required velocity for cooling the fiber end, some systems have used fans that are much larger than necessary for the general cooling requirements. As a result, such fans may consume more electrical power than is necessary for the overall application requirements. Cooling fans have also proven to be noisy, which may severely restrict their use such as in areas where quiet operation is necessary. Furthermore, some fiber optic cable systems incorporating the higher light output of metal halide lamps have been limited in their application. Although these lamps produce more visible light than incandescent and halogen lamps, they also produce more infrared and ultraviolet energy, thereby making it more difficult to provide the necessary cooling to the fiber ends in order to take advantage of these higher output lamps.
In view of the above, it would be advantageous to provide an improved fiber optic lighting system capable of providing a higher level of light intensity to the input end of a fiber optic cable while ensuring that the fiber optic cable is not subjected to damage causing heat. It would also be advantageous to provide a device for coupling light emitted from a high intensity light source to the fiber optic cable that maintains the integrity of the light transmission and focal point in front of the cable, insulates the exposed ends of the fiber optic cable from heat, dissipates heat generated within the system and significantly reduces noise generated by the system.